I examined ~2700 food samples collected from adult and nestling black-legged kittiwakes Rissa tridactyla from 1978 through 2011 on Middleton Island in the Gulf of Alaska. The kittiwake diet was ...composed chiefly of fish, but invertebrates were taken in appreciable quantities in April and May. Upon spring arrival at the colony, adult kittiwakes foraged regularly at night on vertically migrating mesopelagic prey—lanternfishes (Myctophidae), squids, crustaceans, and polychaetes—a behavior they largely discontinued by egg-laying. During incubation and chickrearing, food samples contained mostly (~85% by weight) Pacific sand lance Ammodytes hexapterus, capelin Mallotus villosus, Pacific herring Clupea pallasii, sablefish Anopoploma fimbria, krill (Euphausiidae), and juvenile salmon Onchorynchus gorboscha and O. keta. A salient finding over the longitudinal study was the emergence, twice, of capelin as a dominant forage species—once in 2000 to 2003, and again in 2008 through 2011. Kittiwakes responded to capelin availability by producing markedly higher numbers of fledged young. The 2000 to 2003 event corresponded to a previously documented shift to cooler conditions in the NE Pacific, which apparently was relatively limited in magnitude or duration. The more recent transition appears stronger and may be more lasting. I submit that 2008 was an important turning point, marking a substantive reversal of warm conditions that began with the well-documented regime shift of 1977. That interpretation is consistent with the existence of a ~60 yr cycle in ocean and atmospheric conditions in the North Pacific. All else being equal, it predicts the next 20 to 30 yr will be favorable for species such as kittiwakes and Steller sea lions, which seemed to respond negatively to the 1977 to 2007 warm phase of the Pacific Decadal Oscillation.
The microbiota is suggested to be a fundamental contributor to host reproduction and survival, but associations between microbiota and fitness are rare, especially for wild animals. Here, we tested ...the association between microbiota and two proxies of breeding performance in multiple body sites of the black‐legged kittiwake, a seabird species. First we found that, in females, nonbreeders (i.e., birds that did not lay eggs) hosted different microbiota composition to that of breeders in neck and flank feathers, in the choanae, in the outer‐bill and in the cloacae, but not in preen feathers and tracheae. These differences in microbiota might reflect variations in age or individual quality between breeders and nonbreeders. Second, we found that better female breeders (i.e., with higher body condition, earlier laying date, heavier eggs, larger clutch, and higher hatching success) had lower abundance of several Corynebacteriaceae in cloaca than poorer female breeders, suggesting that these bacteria might be pathogenic. Third, in females, better breeders had different microbiota composition and lower microbiota diversity in feathers, especially in preen feathers. They had also reduced dispersion in microbiota composition across body sites. These results might suggest that good breeding females are able to control their feather microbiota—potentially through preen secretions—more tightly than poor breeding females. We did not find strong evidence for an association between reproductive outcome and microbiota in males. Our results are consistent with the hypothesis that natural variation in the microbiota is associated with differences in host fitness in wild animals, but the causal relationships remain to be investigated.
see also the Perspective by Sondra Turjeman
Flight is a key adaptive trait. Despite its advantages, flight has been lost in several groups of birds, notably among seabirds, where flightlessness has evolved independently in at least five ...lineages. One hypothesis for the loss of flight among seabirds is that animals moving between different media face tradeoffs between maximizing function in one medium relative to the other. In particular, biomechanical models of energy costs during flying and diving suggest that a wing designed for optimal diving performance should lead to enormous energy costs when flying in air. Costs of flying and diving have been measured in free-living animals that use their wings to fly or to propel their dives, but not both. Animals that both fly and dive might approach the functional boundary between flight and nonflight. We show that flight costs for thick-billed murres (Uria lomvia), which are wing-propelled divers, and pelagic cormorants (Phalacrocorax pelagicus) (foot-propelled divers), are the highest recorded for vertebrates. Dive costs are high for cormorants and low for murres, but the latter are still higher than for flightless wing-propelled diving birds (penguins). For murres, flight costs were higher than predicted from biomechanical modeling, and the oxygen consumption rate during dives decreased with depth at a faster rate than estimated biomechanical costs. These results strongly support the hypothesis that function constrains form in diving birds, and that optimizing wing shape and form for wing-propelled diving leads to such high flight costs that flying ceases to be an option in larger wing-propelled diving seabirds, including penguins.
Predicting the impacts of changing environments on phenotypes in wild populations remains a challenge. Growth, a trait that frequently influences fitness, is difficult to study as it is influenced by ...many environmental variables. To address this, we used a sliding window approach to determine the time windows when sea-surface and air temperatures have the potential to affect growth of black-legged kittiwakes (
Rissa tridactyla
) on a colony in the Northeast Pacific. We examined environmental drivers influencing nestling growth using data from a long-term (21-year) study, that food supplements a portion of the colony. The associations between kittiwake growth and climatic conditions in our study indicated that warmer environmental conditions can both positively and negatively impact nestling growth parameters depending on hatching order. We found that first-hatched nestlings had a heavier maximum mass under warm air temperatures and cold sea conditions. Warmer air temperatures negatively affected the second-hatched nestling in a brood. However, when air temperatures were warm, warmer sea-surface temperatures predicted heavy, fast-growing second-hatched nestlings in contrast to what we observed for first-hatched nestlings. Food supplementation alleviated the temperature effects, and competition among nestlings influenced how strongly a variable affected growth. We identified windows that might indicate specific biological pathways through which environmental variation affected growth directly or indirectly. Overall, our windows suggest that nestlings in shared nests will be most affected by warming conditions.
Abstract
Theory predicts that parental heritable characteristics should shape sex allocation decisions when their effects on reproduction or survival are offspring sex-dependent. Numerous studies ...have questioned to what extent characteristics displayed by one of the parents matched theoretical expectations. This contrasts with the handful of studies that investigated whether compatibility between parents could also trigger selective pressures for sex allocation adjustments. We studied the genetically monogamous black-legged kittiwake (Rissa tridactyla), where previous data revealed that female chicks suffered higher fitness costs from low diversity at genes of the major histocompatibility complex (MHC) than male chicks. We predicted, and found in our dataset, that MHC-similar parents, producing low MHC-diverse offspring, should avoid the production of females. The relation between MHC-distance between parents (i.e. the functional distinctness of their MHC alleles) and offspring sex was not linear, such that MHC-dissimilar parents also overproduced sons. Overall, our results suggest that the genetically monogamous black-legged kittiwake parents flexibly adapt their reproduction and circumvent the costs of suboptimal pairing by manipulating offspring sex.
When parental characteristics affect offspring reproduction or survival in a sex-dependent way, parents should choose to have the sex that performs best. In the black-legged kittiwake, a lack of diversity at immune genes has strong negative effects in daughters, but not in sons. Accordingly, we show that when kittiwake parents are at risk of producing low genetically diverse offspring, they avoid producing daughters. Our results further suggest that it may be advantageous for parents to produce high genetically diverse sons.
Climate change is altering species' traits across the globe. To predict future trait changes and understand the consequences of those changes, we need to know the environmental drivers of phenotypic ...change. In the present study, we use multi‐decadal long datasets to determine periods of within‐year environmental variation that predict growth of three seabird species. We evaluate whether these periods changed over time and use them to predict future growth under climate change. We find that predictions of trait change could be improved by considering that 1) the timing of environmental factors used to predict traits (predictive‐environmental features) can change over time, and 2) the type of predictive‐environmental features can change over time. We find evidence of changes in the timing of environmental predictors in all populations studied and evidence for a change in the type of predictor in the studied Arctic murre population. Environmental models of growth predict that warming conditions will decrease growth rates and bird body sizes in two species (black‐legged kittiwake Rissa tridactyla and glaucous‐winged gull Larus Larus glaucescens), but not the third (thick‐billed murre Uria lomvia). Consequently, climate change is likely to decrease fledging rates in the gulls and kittiwakes. Further, we find that sea ice‐cover historically predicted murre chick growth well, but no longer does – instead air temperature is now a better predictor of murre growth. Our study highlights a need to investigate whether environmental determinants of trait variation commonly shift in a changing climate and whether such changes have implications for adaptation to novel environments.
Marine heatwaves are increasing in frequency and can disrupt marine ecosystems non-linearly. In this study, we examined the effect of the North Pacific warming event of 2014, the largest long-term ...sea surface anomaly on record, on black-legged kittiwake Rissa tridactyla foraging trips before, during, and after the event. We assessed foraging trip characteristics (trip distance and duration), the dispersal of foraging locations, and the persistence of foraging areas within and among years. Foraging trip characteristics, foraging area size, and location varied from year to year. Kittiwake foraging was more dispersed, direct, and farther from the colony in years immediately after and during the warming event. A third of the foraging area used pre-heatwave (2012) was important in subsequent years, which indicates that this area was, and may still be, a perennial foraging hot spot. During the chick-rearing stage, black-legged kittiwakes increased their speed and reduced the proportion of resting compared to the incubation stage. We conclude that marine heatwaves may have a strong impact on seabird foraging, extending foraging ranges, and that those impacts may be nonlinear with a strong lag.
Biologging has revealed many of the mysteries surrounding seabird behavior far from land. However, tagging seabirds with biologgers may influence the very traits they are designed to observe. Such ...‘tag effects’ are often argued to be minimal below a threshold of 3% of body mass. Nonetheless, few studies carefully separate handling from tagging effects, so the effect of tag size is often confounded with the effect of handling. Puffins, including rhinoceros auklets Cerorhinca monocerata, are notoriously difficult to work with due to high nest abandonment rates. To examine tagging and handling effects in rhinoceros auklets, we compared abandonment rates of individuals equipped with a GPS weighing ~2.3% of body mass with abandonment rates of birds handled but not equipped, and of birds not handled at all (controls). We used the egg flotation technique to estimate egg development and predict hatching date, thus allowing treatments to be applied at the appropriate time. Handling more than doubled abandonment rates compared to control birds, and tagging more than doubled abandonment rates compared to birds that were handled but not tagged. Abandonment rates decreased as incubation progressed and were lowest during chick-rearing. We conclude that both handling and tagging of auklets increase abandonment, and that effects are lowest during chick-rearing.
Seasonal timing of breeding is usually considered to be triggered by endogenous responses linked to predictive cues (e.g., photoperiod) and supplementary cues that vary annually (e.g., food supply), ...but social cues are also important. Females may be more sensitive to supplementary cues because of their greater role in reproductive timing decisions, while males may only require predictive cues. We tested this hypothesis by food-supplementing female and male colonial seabirds (black-legged kittiwakes, Rissa tridactyla) during the pre-breeding season. We measured colony attendance via GPS devices, quantified pituitary and gonadal responses to gonadotropin releasing hormone (GnRH) challenge, and observed subsequent laying phenology. Food supplementation advanced laying phenology and increased colony attendance. While female pituitary responses to GnRH were consistent across the pre-breeding season, males showed a peak in pituitary sensitivity at approximately the same time that most females were initiating follicle development. The late peak in male pituitary response to GnRH questions a common assumption that males primarily rely on predictive cues (e.g., photoperiod) while females also rely on supplementary cues (e.g., food availability). Instead, male kittiwakes may integrate synchronising cues from their social environment to adjust their reproductive timing to coincide with female timing.
•Food supplementation advanced laying phenology and increased time at colony.•Hormones and attendance of both sexes responded similarly to feeding.•Both sexes appear to be integrating information to time reproduction.•Male pituitary responses to GnRH peaked after females during pre-breeding.•Males may integrate synchronising cues to match with female timing decisions.
The magnitude of climate change has been greatest in the Arctic, accelerating climate‐induced shifts in phenology, but wildlife responses vary. Variation may be due to the relative importance of ...phenotypic plasticity or phenotypic selection.
Here, we examine and contrast the environmental drivers of plasticity in breeding phenology of two circumpolar seabirds at their receding summer range limit using unique datasets of marked individuals covering 25 and 30 years. Based on prior knowledge of the local ecosystems, we predicted that climate would generate opposing patterns of plasticity in the two populations.
Laying phenology of kittiwakes in the Gulf of Alaska was associated with a large‐scale climate oscillation (Pacific Decadal Oscillation) while the Arctic‐breeding murres adjusted laying to sea‐ice conditions. Kittiwakes laid earlier after experiencing colder climate about 2 years prior and laying dates did not advance over the study, but murres laid earlier when warmer climate led to earlier spring sea‐ice break‐up, and murre laying dates advanced by 1 week since 1990. Selection favoured earlier laying in both species.
Both populations adjusted breeding phenology to environmental variation, but we anticipate opposing effects on phenology with continued climate change. Ice‐constrained species can likely adapt to some extent because plasticity can provide the necessary shift to this physical barrier, although individuals were only able to adjust by ~1 week while ice conditions advanced by over a month. In more temperate regions, where phenology is driven by bottom‐up effects, plasticity and selection counteract one another leading to limited adaptability. We provide insights into the likely adjustments by Arctic marine animals to an increasingly warmer and ice‐less summer.
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